Axial Fan

ABSTRACT

An axial fan is provided which has a high degree of freedom of design of a condition of gas to be discharged. An axial fan  1  of the present disclosure comprises a discharge port; a rotation axis; an impeller  23 ; and a casing  30  including a side wall  31  part that encloses the impeller  23 , wherein the side wall part  31  includes a plurality of inner face parts  37   a   1  in a circumferential direction on the discharge port  2  side, and an inner face part angle is an angle of the inner face part  37   a   1  with respect to the rotation axis, and the inner face part angle on an outwardly spreading side with respect to the rotation axis is a positive angle, and the inner face part angles are greater than 0°, and the two inner face parts adjacent to each other have different inner face part angles.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Applications No. 2016-010298, filed Jan. 22, 2016 and No. 2017-001893, filed on Jan. 10, 2017 which are hereby incorporated by reference in their entirety.

BACKGROUND

Technical Field

The present disclosure relates to an axial fan.

Background

Japanese Patent Application Laid-Open No. 2006-063972 discloses an axial fan comprising a casing, wherein a discharge port side of the casing is formed into a tapered shape that spreads in a direction in which air is discharged, and can thereby orient a wind direction toward a wider range.

On the other hand, Japanese Patent Publication No. 5839755 discloses an axial fan comprising a casing, wherein a discharge port side of the casing is formed into a substantially straight shape, and such an axial fan is considered to form an air flow with a small spreading range of wind direction.

SUMMARY

Although the axial fans disclosed in Japanese Patent Application Laid-Open No. 2006-063972 and Japanese Patent Publication No. 5839755 are different in the range of air discharged from the discharge port, both axial fans are assumed to have a circular blowing range.

However, depending on use, the blowing range may preferably have an elliptical shape.

Furthermore, in the axial fan, since members constituting a motor such as a stator part or a rotor part are located in the center, air is discharged in an annular shape from the discharge port and if the air discharged in the annular shape is guided so as to spread as in the case of the axial fan according to Japanese Patent Application Laid-Open No. 2006-063972, there is not much air flow in the center of the blowing range, and therefore when a cooling target is small, there is a problem that the cooling efficiency is not high.

On the other hand, when the range of the wind direction is narrowed as in the case of Japanese Patent Publication No. 5839755, if the cooling target is small, the wind can be blown over the cooling target efficiently, but, in contrast, if the cooling target is large, it is not possible to blow the wind over the entire cooling target, which results in a problem of low cooling efficiency.

In consideration of such problems, providing an axial fan which has a relatively wide blowing range and also has an air flow on the center side of the blowing range will make it possible to suitably cool the cooling target regardless of the size of the cooling target.

Therefore, there is a demand for an axial fan including a high degree of freedom of design of a condition of the gas to be discharged such as air, by adopting an elliptical shape for the blowing range, including a relatively wide blowing range and the ability to form an air flow also on the center side of the blowing range.

One of the objects of the present disclosure is to provide an axial fan including a high degree of freedom of design of a condition of gas to be discharged.

According to a first aspect of the present disclosure,

(1) an axial fan comprises a discharge port; a rotation axis; an impeller; and a casing including a side wall part that encloses the impeller, wherein the side wall part includes a plurality of inner face parts in a circumferential direction on the discharge port side, and an inner face part angle is an angle of the inner face part with respect to the rotation axis, and the inner face part angle on an outwardly spreading side with respect to the rotation axis is a positive angle, and the inner face part angles are greater than 0°, and the two inner face parts adjacent to each other have different inner face part angles. (2) In the configuration (1) above, the inner face parts are arranged to be lined in a circumferential direction. (3) In the configuration (1) above, the number of the inner face parts is two. (4) In the configuration (1) above, the number of the inner face parts is three or more. (5) In the configuration (4) above, the number of the inner face parts is an even number, and two of the inner face parts facing in a radial direction include a same inner face part angle. (6) In the configuration (1) above, the casing includes an opening part as the discharge port, and the number of the inner face parts is two, and one of the inner face parts has a range less than half of an inner peripheral end part provided in the side wall part on the opening part side, with respect to an entire circumference of the inner peripheral end part in the circumferential direction. (7) In any one of the configurations (1) above, a height of the inner face part is equal to or less than ⅓ of a height of the side wall part in a rotation axis direction.

According to the present disclosure, for example it is possible to provide an axial fan including a high degree of freedom of design of a condition of the discharged gas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an axial fan of a first embodiment according to the present disclosure seen from a discharge port side.

FIG. 2 is a cross-sectional view along a line A-A in FIG. 1.

FIG. 3 is a cross-sectional view similar to FIG. 2 and is a diagram provided for describing a discharge port side inner peripheral face of the first embodiment.

FIG. 4 is a plan view schematically illustrating a blowing range of a gas discharged from a discharge port of the axial fan of the first embodiment.

FIG. 5 is a graph illustrating characteristics of the axial fan of the first embodiment and characteristics of a conventional axial fan.

FIG. 6 is a plan view of an axial fan according to a modification of the first embodiment seen from the discharge port side.

FIG. 7 is a plan view schematically illustrating a blowing range of a gas discharged from a discharge port of the axial fan of the modification of the first embodiment.

FIG. 8 is a plan view schematically illustrating an axial fan according to a second embodiment of the present disclosure seen from the discharge port side.

DETAILED DESCRIPTION

Hereinafter, modes for implementing the present disclosure (hereinafter referred to as “embodiments”) will be described in detail based on the accompanying drawings.

Note that identical elements throughout the whole description of the embodiments will be assigned by identical reference numerals.

First Embodiment

FIG. 1 is a plan view of an axial fan 1 of a first embodiment according to the present disclosure seen from a discharge port 2 side and FIG. 2 is a cross-sectional view along a line A-A in FIG. 1.

The first embodiment will describe an axial fan in which a blowing range of a gas such as air to be discharged from the discharge port 2 of the axial fan 1 can be an elliptical shape.

As shown in FIG. 2, the axial fan 1 comprises an intact port 2 of gas, a discharge port 2 of gas, a stator part 10, a rotor part 20 including an impeller 23 and a casing 30 including a side wall part 31 that encloses an outer periphery (an outer peripheral part) of the impeller 23.

(Stator Part)

As shown in FIG. 2, the stator part 10 comprises a stator core 11 formed by stacking a plurality of electromagnetic steel sheets, an insulator 12 provided at an outer periphery part of the stator core 11, and a coil 13 wound around the stator core 11 via the insulator 12.

The stator core 11 is fixed to an outer periphery part of a bearing housing 34 formed in a base part 32 of the casing 30 which will be described later, using a fixing means such as press fitting or adhesion.

(Rotor Part)

As shown in FIG. 2, the rotor part 20 comprises a shaft 21 that becomes a rotation axis of the rotor part 20, a yoke 22 fixed to the shaft 21 and formed with a cup shape including an open end on the discharge port 2 side, the impeller 23 including a hub 23 a fixed to the shaft 21 so as to cover the outside of the yoke 22 and a plurality of blades 23 b provided at the outer peripheral part of the hub 23 a and a magnet 24 attached to an inner face of the yoke 22.

A blade 23 b includes a side part 23 b 1 arranged on the intake port 3 side and a side part 23 b 2 arranged on the discharge port 2 side and a side part 23 b 3 arranged between the side part 23 b 1 and the side part 23 b 2 and two side faces 23 b 4, 23 b 5 facing other adjacent blades 23 b. The side parts 23 b 1, 23 b 2, 23 b 3 forms a side face as an outer periphery of the blade 23 b and are arranged between two side faces 23 b 4, 23 b 5 in a direction of a thickness of the blade 23 b.

In a FIG. 2, the side part 23 b 1 arranged on the intake port 3 side is formed with a curved shape toward the intake port 3.

And the side part 23 b 1 includes a top part 23 b 6 arranged on the intake port 3 side.

In a FIG. 2, the side part 23 b 2 arranged on the discharge port 2 side is formed with a curved shape toward the discharge port 2 side.

And the side part 23 b 2 includes a top part 23 b 7 arranged on the discharge port 2 side.

In FIG. 2, the side part 23 b 1 includes a bending portion on the side part 23 b 3 side. The bending portion of the side part 23 b 2 includes a top part 23 b 6.

And In FIG. 2, the side part 23 b 2 includes a bending portion on the side part 23 b 3 side. The bending portion of the side part 23 b 2 includes a top part 23 b 7. A bending part is formed with the bending portion of the side part 23 b 1 and the bending portion of the side part 23 b 2.

The side part 23 b 3 faces an inner peripheral face 36 of the casing 30 in a radial direction.

The side part 23 b 3 facing the inner peripheral face 36 of the casing 30 is formed with a planar shape and extends toward the side part 23 b 2 from the side part 23 b 1 in FIG. 2.

And two side faces 23 b 4, 23 b 5 face each other in a circumferential direction or in a rotation direction of the rotation axis.

The shaft 21 is rotatably supported by a pair of rolling bearings 35 provided on one end side and the other end side in the bearing housing 34.

For this reason, the rotor part 20 is configured to be rotatable with respect to the stator part 10.

(Casing)

As shown in FIG. 1 and FIG. 2, the casing 30 comprises a side wall part 31 that encloses an outer peripheral part of the impeller 23 (blade 23 b), a base part 32 including the bearing housing 34 in which the stator part 10 and the rotor part 20 are provided and a connection part 33 (see FIG. 1) that connects the side wall part 31 and the base part 32.

The casing includes two opening part 30 a, 30 b in the rotation axis direction (in a direction of the shaft 21 extending).

The one opening part 30 b of these two opening 30 a, 30 b, is the discharge port 2.

The one opening part 30 b is surrounded by an inner peripheral end part 37 c of the side wall part 31.

The discharge port 2 is surrounded by the inner peripheral face 36 of the side wall part 31 of the casing 30.

In the axial fan 1 shown in FIG. 1, the discharge port 2 is arranged inside the inner peripheral face 36 of the side wall part 31 (FIG. 2) and formed with a range except the base part 32 and connection parts 33.

In FIG. 2, the intake port 3 of gas is the one opening part 30 a on the hub 23 a side of the casing 30 while the discharge port 2 of the gas is the one opening part 30 b on the base part 32 side of the casing 30.

As shown in the FIG. 2, the inner peripheral face 36 of the side wall part 31 includes a curved part 37 d arranged on the intake port 3 side and a discharge port side inner peripheral face 37 (FIG. 3) and a planer part 37 e positioned between the curved part 37 d and the discharge port side inner peripheral face 37.

The curved part 37 d and the planer part 37 e are formed in an annual shape in a circumferential direction.

the discharge port side inner peripheral face 37 of the side wall part 31 is arranged between the top part 23 b 7 on the discharge port 2 side and the inner peripheral end part 37 c (FIG. 1) in the rotation axis direction and arranged on the discharge port 2 side with respect to one end part of the side part 23 b 3 (an end part on the side part 23 b 2 side)

In the present embodiment, the bearing housing 34 is integrally molded with the base part 32, but the bearing housing 34 as a separate part may be attached to the base part 32, or the bearing housing 34 as a separate part and the casing 30 may be integrally molded when the casing 30 is molded.

Furthermore, although the connection parts 33 are spokes in the present embodiment, the connection parts 33 need not be limited to the spokes, but may also be stator vanes or the like.

According to the present embodiment configured as described above, when the rotor part 20 including the impeller 23 rotates, the axial fan 1 takes in a gas such as air from an intake port 3 side shown in FIG. 2 (upper side in FIG. 2), the gas taken in from the intake port 3 is guided by an inner peripheral face 36 of the side wall part 31 of the casing 30 and sent to the discharge port 2 side and the gas is blown outside the axial fan 1 from the discharge port 2.

Next, the inner peripheral face 36 of the side wall part 31 of the casing 30 that guides this gas flow will be described in further detail with reference to FIG. 3.

FIG. 3 is a cross-sectional view similar to FIG. 2 and is a figure to explain a discharge port side inner peripheral face 37 of the first embodiment.

In FIG. 3, a Z-axis shown by a single-dot dashed line is a rotation axis of the shaft 21 and a Z′-axis shown by a two-dot dashed line is an axis parallel to the Z-axis.

As shown in FIG. 3, the side wall part 31 of the casing 30 includes inner peripheral face 37 provided within a predetermined range h in the rotation axis (see the Z-axis) direction of the rotor part 20 from an end part 31 a on the discharge port 2 side from which the gas is discharged. The inner peripheral face (referred to as the discharge port side) is arranged the discharge port side.

Specific details will be described later. The discharge port side inner peripheral face 37 is provided within the predetermined range h. In the rotation axis (see the Z-axis) direction of the rotor part 20, the predetermined range h is preferably a range equal to or less than ⅓ of a height H of the side wall part 31 from an end part 31 a of the side wall on the discharge port 2 side part 31. In the present embodiment, the predetermined range h is set to be substantially ⅓ of the height H.

As shown in FIG. 1 and FIG. 3, the discharge port side inner peripheral face 37 includes a plurality of inner face parts 37 a 1 and 37 b 1 in the circumferential direction of the discharge port side inner peripheral face 37. The inner face parts 37 a 1 and 37 b 1 are formed so as to have different inclined states each other.

To describe more specifically with reference to FIG. 3, as shown in an enlarged view circled by a dotted line in FIG. 3, the inner face part 37 a 1 is formed to have a state inclined at an angle of θ1 (tapered state) with respect to the Z′-axis The Z′-axis is an axis parallel to the rotation axis (see the Z-axis) of the rotor part 20 of the inner face part 37 a 1.

Note that since the Z′-axis is an axis parallel to the Z-axis, the angle θ1 is likewise applicable to the Z-axis, and hereinafter the Z′-axis will be described as the rotation axis of the rotor part 20.

That is, when the angle of the inner face part 37 a 1 with respect to the rotation axis (see the Z′-axis) of the rotor part 20 is assumed to be an inner face part angle and the inner face part angle on the outwardly spreading side with respect to the rotation axis (see the Z′-axis) is assumed to be a positive angle, the inner face part 37 a 1 on the discharge port 2 side is designed to have an inner face part angle at least greater than 0°.

Note that in the present embodiment, the inner face part 37 a 1 is formed with two inclined faces that the angle of inclination on the discharge port 2 side of the inner face part 37 a 1 differs the angle of inclination on the side close to the blade 23 b. But the inner face part 37 a 1 need not always have a two inclined face, and may have a single inclined face that the angle of inclination is substantially the same for an overall length along the rotation axis (see the Z′-axis) of the rotor part 20 of the inner face part 37 a 1.

Similarly, as shown in an enlarged view circled by a dotted line in FIG. 3, when the angle of the inner face part 37 b 1 with respect to the rotation axis (see the Z′-axis) of the rotor part 20 is assumed to be an inner face part angle and the inner face part angle on the outwardly spreading side with respect to the rotation axis (see the Z′-axis) is assumed to be a positive angle, the inner face part 37 b 1 is designed so that the inner face part angle on the discharge port 2 side has an angle θ2 at least greater than 0°.

Note that in the present embodiment, the angle θ2 is such a small degree of angle necessary for die cutting when the casing 30 is molded, and so the angle θ2 is not 0° but close to 0°.

In the present embodiment, a part with angle θ1 in the inner face part 371 a is arranged on the discharge port 2 side with respect to the top part 23 b 7 on the discharge port 2 side in the discharge port side inner peripheral face 37.

Other inner face parts except the inner face part 37 a 1 (for example, the inner face part 37 b 1) are similar to the inner face part 37 a 1. A part with angle θ2 in other inner face part is arranged on the discharge port 2 side with respect to the top part 23 b 7 on the discharge port 2 side in the discharge port side inner peripheral face 37.

Additionally, the discharge port side inner peripheral face 37 may be arranged only on the discharge port 2 side with respect to the top part 23 b 7 arranged on the discharge port 2 side. An inner face part may be arranged only on the discharge port 2 side with respect to the top part 23 b 7 arranged on the discharge port 2 side.

Thus, in the respective inner face parts 37 a 1 and 37 b 1, inner face part angles on the discharge port 2 side are at least greater than 0°, and in addition, there is a relationship of angle θ1>angle θ2, and therefore the inner face parts 37 a 1 and 37 b 1 adjacent to each other in the circumferential direction have different inner face part angles on the discharge port 2 side.

In the present embodiment, the inner face part 37 a 1 is provided within a range of 180° as shown by a bidirectional arrow with a solid line in FIG. 1 seen from the circumferential direction of the discharge port side inner peripheral face 37 and the inner face part 37 b 1 is provided within a range of the remaining 180° as shown by a bidirectional arrow with a dotted line in FIG. 1 seen from the circumferential direction of the discharge port side inner peripheral face 37.

For this reason, the inner face parts 37 a 1 and 37 b 1 are parts of the discharge port side inner peripheral face 37 divided into substantially equal portions in the circumferential direction.

That is, a range covered with each of the inner face parts 37 a 1 and 37 b 1 is a half range with respect to a whole circumference of the inner peripheral end part 37 c of the side wall part 31 on the discharge port 2 side.

But, the range covered with one of the inner face parts 37 a 1 and 37 b 1 is narrower than a half range with respect to a whole circumference of the inner peripheral end part 37 c of the side wall part 31 on the discharge port 2 side.

For example, the range covered with the inner face parts 37 a 1 may be within one-fourth range with respect to a whole circumference of the inner peripheral end part 37 c. The range covered with the inner face parts 37 b 1 may be within three-fourth range with respect to a whole circumference of the inner peripheral end part 37 c.

While, the range covered with the inner face parts 37 a 1 may be within three-fourth range with respect to a whole circumference of the inner peripheral end part 37 c. The range covered with the inner face parts 37 b 1 may be within one-fourth range with respect to a whole circumference of the inner peripheral end part 37 c.

And, heights of the inner face parts 37 a 1 and 37 b 1 forming the discharge port side inner peripheral face 37 are equal to or less than one-third height H of the side wall part 31 with respect to an end part 31 a of the side wall part 31 on the discharge port 2 side.

The gas flow guided by the inner face part 37 a 1 and discharged from the discharge port 2 spreads outward. But on the other hand, the gas flow guided by the inner face part 37 b 1 and discharged from the discharge port 2 does not spread outward much.

FIG. 4 is a diagram schematically illustrating a blowing range W of a gas discharge from the discharge port 2 of the axial fan 1 in such a gas discharge condition, and as shown in FIG. 4, the gas discharged from the axial fan 1 describes an elliptical blowing range W. Note that the base part 32 and the connection parts 33 are omitted in FIG. 4.

Note that FIG. 4 is merely a schematic view, and since the gas flow discharged from the discharge port 2 of the axial fan 1 is a revolving flow, the elliptical shape showing the blowing range W may be rotated about a predetermined angle θ in a gas revolving direction Y.

Otherwise, a long direction al or a short direction 131 of the elliptical shape showing the rotated blowing range W1 may be rotated about the predetermined angle θ in the revolving direction Y with respect to the a long direction a or a short direction 13 of the elliptical shape.

Here, as is clear from FIG. 4, the axial fan 1 of the present embodiment is configured such that the gas is discharged on one side (right side in FIG. 4) with respect to the casing 30, and therefore it is suitable for, for example, when the gas need not be blown toward the other side (left side in FIG. 4) with respect to the casing 30.

In a case the inner face part 37 a 1 in FIG. 4 is replaced to the inner face part 37 b 1 and the inner face part 37 b 1 is replaced to the inner face part 37 a 1, the gas can be blown toward the other side (left side in FIG. 4) with respect to the casing 30.

Hence, in the axial fan 1 of the present embodiment it is suitable for, for example, when the gas need be blown toward one side or the other side with respect to the casing 30.

Note that when a large gap or the like exists between the inner peripheral face 36 (see FIG. 2) of the side wall part 31 and the blade 23 b, the characteristics (static pressure-air quantity characteristic, static pressure efficiency or the like) of the axial fan 1 may deteriorate.

Since the discharge port side inner peripheral face 37 is inclined (tapered) outward, if the discharge port side inner peripheral face 37 is provided next to the blade 23 b in a radial direction, the gap between the discharge port side inner peripheral face 37 and the blade 23 b may increase in size, causing the characteristics of the axial fan 1 to deteriorate.

For this reason, as described with reference to FIG. 3, the predetermined range h is preferably a range equal to or less than ⅓ of the height H of the side wall part 31 in the rotation axis (see the Z-axis) direction of the rotor part 20 from the end part 31 a of the side wall part 31 on the discharge port 2 side and the discharge port side inner peripheral face 37 is preferably not provided so closely next to the blade 23 b. And, the discharge port side inner peripheral face 37 is preferably arranged only on the discharge port2 side with respect to the top part 23 b 7 arranged on the discharge port2 side. An inner face part is preferably arranged only on the discharge port 2 side with respect to the top part 23 b 7 arranged on the discharge port 2 side.

A deterioration of a characteristics (static pressure-air quantity characteristic, static pressure efficiency or the like) of the axial fan can be prevented.

However, even when the predetermined range h is a range greater than ⅓ of the height H of the side wall part 31 in the rotation axis (see the Z-axis) direction of the rotor part 20 from the end part 31 a on the discharge port 2 side of the side wall part 31, in some cases there may be substantially no influence on the characteristics (static pressure-air quantity characteristic, static pressure efficiency or the like) of the axial fan 1, and therefore in above cases the predetermined range h may be set to be equal to or less than ⅓ of the height H of the side wall part 31.

Therefore, when the discharge port side inner peripheral face 37 may possibly affect the characteristics (static pressure-air quantity characteristic, static pressure efficiency or the like) of the axial fan 1, the predetermined range h is provided is preferably set to be equal to or less than ⅓ of the height H of the side wall part 31.

Note that, for example, even when it is not clear in the design stage whether or not the discharge port side inner peripheral face 37 affects the characteristics (static pressure-air quantity characteristic, static pressure efficiency or the like) of the axial fan 1, if the predetermined range h is set to be equal to or less than ⅓ of the height H of the side wall part 31, it is not so necessary to consider influences on the characteristics (static pressure-air quantity characteristic, static pressure efficiency or the like) of the axial fan 1, and it is thereby possible to reduce the strain imposed on the design if the predetermined range h in which the discharge port side inner peripheral face 37 is provided is set to be equal to or less than ⅓ of the height H of the side wall part 31.

[Characteristics of Axial Fan of First Embodiment]

FIG. 5 is a graph illustrating the characteristics (static pressure-air quantity characteristics and static pressure efficiency (=(static pressure×air quantity)/power consumption)) of the axial fan 1 of the aforementioned configuration of the first embodiment, that is, illustrating the characteristics (static pressure-air quantity characteristics and static pressure efficiency) of the axial fan 1 whose discharge port side inner peripheral face 37 has two inner face parts 37 a 1 and 37 b 1 including different inner face part angles in the circumferential direction, and characteristics (static pressure-air quantity characteristics and static pressure efficiency) of a conventional axial fan.

In the axial fan 1 of the practical example, the discharge port side inner peripheral face 37 includes two inner face parts 37 a 1 and 37 b 1 including different inner face part angles and a range of 180° of 360° in the circumferential direction of the discharge port side inner peripheral face 37 is designated as the inner face part 37 a 1 and a remaining range of 180° is designated as the inner face part 37 b 1.

On the other hand, the axial fan in the comparative example is only different from the axial fan 1 of the example in that the entire circumference of 360° in the circumferential direction of the discharge port side inner peripheral face 37 is set to the same condition as the inner face part 37 a 1 of the axial fan 1 of the example and there is no part where the inner face part angle is different in the circumferential direction, and the rest is the same as the axial fan 1 of the example.

The horizontal axis in FIG. 5 denotes an air quantity [m³/min] and the vertical axis for data shown by circle-marked sample points denotes a static pressure [Pa].

The horizontal axis in FIG. 5 denotes an air quantity [m³/min] and the vertical axis for data shown by triangle-marked sample points denotes static pressure efficiency [%].

Note that in the graph shown in FIG. 5, data of solid filled sample points denotes data of the axial fan 1 of the example and data of outlined sample points denotes data of the axial fan in the comparative example.

As shown in FIG. 5, the axial fan 1 of the example has substantially the same characteristics of both static pressure-air quantity characteristics and static pressure efficiency as those of the axial fan of the comparative example, and even when the discharge port side inner peripheral face 37 has the inner face parts 37 a 1 and 37 b 1 including different inner face part angles, it is understood that no deterioration has occurred in the characteristics aspect of the axial fan.

Modification of First Embodiment

In the axial fan 1 of the first embodiment, the center of the elliptical blowing range W is offset from the center of the discharge port 2 as shown in FIG. 4, but when the elliptical blowing range W is preferred to be symmetric with respect to the center of the discharge port 2, the axial fan 1 may be configured as shown in the following modification.

FIG. 6 is a plan view of an axial fan V according to a modification of the first embodiment seen from the discharge port 2 side, and since the basic configuration is similar to that of the first embodiment, the following description will focus on differences from the first embodiment and description of similar configurations may be omitted.

In the axial fan 1 of the first embodiment, the discharge port side inner peripheral face 37 has two inner face parts 37 a 1 and 37 b 1.

On the other hand, as shown in FIG. 6, the axial fan V according to the modification of the first embodiment is different from the first embodiment in that the axial fan V has the discharge port side inner peripheral face 37 divided into four substantially equal portions in the circumferential direction as inner face parts, therefore the discharge port side inner peripheral face 37 including four inner face parts: inner face part 37 a 1 (see a range indicated by an arrow with a solid line), 37 b 1 (see a range indicated by an arrow with a dotted line), 37 a 2 (see a range indicated by an arrow with a solid line), and 37 b 2 (see a range indicated by an arrow with a dotted line). In the side wall part 31, four inner face parts divide the discharge port side inner peripheral face 37 into four substantially equal portions in the circumferential direction. These four inner face parts 37 a 1 37 b 1 37 a 2 37 b 2 are arranged in an equal interval in the circumferential direction.

The inner face part 37 a 1 and the inner face part 37 a 2 face each other across the center of the axial fan r (that is, the rotation axis of the rotor part 20). Namely, the inner face part 37 a 1 and the inner face part 37 a 2 face each other in a radial direction.

These the inner face part 37 a 1 and the inner face part 37 a 2 at least the has an angle θ1 greater than 0° on the discharge port 2 side as in the case of the inner face part 37 a 1 of the first embodiment. Namely, the inner face part 37 a 1 and the inner face part 37 a 2 facing each other in a radial direction have same angle θ1.

Furthermore, the inner face part 37 b 1 and the inner face part 37 b 2 facing each other across the center of the axial fan 1′ (that is, the rotation axis of the rotor part 20) at least have inner face part angles θ2 greater than 0° similarly to the inner face part 37 b 1 of the first embodiment.

Namely, the inner face part angle of the inner face part 37 b 1 and the inner face part 37 b 2 facing each other in the radial direction have same angles θ2.

Therefore, no matter which inner face37 a 1, 37 b 1, 37 a 2, 37 b 2 is used as a reference, the inner face parts adjacent to each other in the circumferential direction have different inner face part angles on the discharge port 2 side as in the case of the first embodiment.

In the modification exactly as described in the first embodiment, the gas flow guided by the inner face parts 37 a 1 and 37 a 2 facing each other and discharged from the discharge port 2 spreads outward, whereas the gas flow guided by the inner face parts 37 b 1 and 37 b 2 facing each other and discharged from the discharge port 2 does not spread outward much.

For this reason, the blowing range W of the gas discharged from the discharge port 2 has an elliptical shape as in the case of the first embodiment.

Moreover, since the inner face parts 37 a 1 and 37 a 2 that guide the gas flow so as to spread outward are provided symmetrically across the center of the axial fan 1 (that is, the rotation axis of the rotor part 20), the blowing range W spreads based on the center of the axial fan 1 (that is, the rotation axis of the rotor part 20) in an elliptical shape. The inner face parts 37 a 1 and 37 a 2 is provided line-symmetrically with respect to the center of the axial fan 1.

It is FIG. 7 that schematically illustrates the blowing range W of the gas discharged from the discharge port 2 of the axial fan V in such a gas discharge condition.

Note that the base part 32 and the connection part 33 are omitted in FIG. 7.

As shown in FIG. 7, while the axial fan 1′ of the modification has an elliptical blowing range W similar to that of the first embodiment, the center of the blowing range W substantially coincides with the center of the axial fan 1′ (that is, the rotation axis of the rotor part 20) and the elliptical blowing range W can be made symmetric with respect to the discharge port 2 as the center. In other words the blowing range W is line-symmetry with respect to a diagonal line of the casing 30.

Although cases have been described so far where the blowing range W of the gas such as air discharged from the discharge port 2 of the axial fan 1 or V has an elliptical shape, the present disclosure is not limited to the above-described specific example.

In the first embodiment and its modification, both the inner face part including the inner face part angle of θ1 and the inner face part including the inner face part angle of θ2 are provided so as to cover the ranges of the same ratio in the circumferential direction of the discharge port side inner peripheral face 37.

More specifically, in the first embodiment, both of the two inner face parts 37 a 1 and 37 b 1 are provided so as to cover the range of 180° of 360° in the circumferential direction of the discharge port side inner peripheral face 37 respectively.

In the modification, all of the four inner face parts 37 a 1, 37 a 2, 37 b 1 and 37 b 2 are provided so as to cover the range of 90° of 360° in the circumferential direction of the discharge port side inner peripheral face 37 respectively.

However, the plurality of inner face parts provided need not cover ranges of the same ratio in the circumferential direction of the discharge port side inner peripheral face 37 respectively.

In the two inner face parts 37 a 1 and 37 b 1 of the first embodiment, for example, the inner face part 37 a 1 may cover the range of 90° of 360° in the circumferential direction of the discharge port side inner peripheral face 37 and the inner face part 37 b 1 may cover the remaining range of 270° of 360° in the circumferential direction of the discharge port side inner peripheral face 37, and the blowing range W has an elliptical shape in this case, too.

In the first embodiment and its modification, the number of the inner face parts is an even number (2 or 4), but the number of the inner face parts may also be an odd number, for example, 3.

In this case, by changing the inner face part angles of the three inner face parts, the inner face parts adjacent to each other in the circumferential direction have different inner face part angles, and by adjusting the respective inner face part angles, it is possible to change the shape of the blowing range W to an elliptical shape resembling an egg.

Second Embodiment

An axial fan has been described in the first embodiment according to which the blowing range W of a gas such as air discharged from the discharge port 2 of the axial fan 1 can have an elliptical shape.

However, the configuration in which the discharge port side inner peripheral face 37 has a plurality of inner face parts in the circumferential direction and the inner face parts adjacent to each other in the circumferential direction have different inner face part angles is not limited to the configuration in which the blowing range W has an elliptical shape, but a configuration may also be adopted in which the blowing range W is a circular and relatively wide shape to form wind which also has an air flow on the center side of the blowing range W.

A second embodiment will describe an axial fan 1″ that has a configuration in which the discharge port side inner peripheral face 37 has a plurality of inner face parts in the circumferential direction, the inner face parts adjacent to each other in the circumferential direction have different inner face part angles, the blowing range W has a circular and relatively wide shape and an air flow exists on the center side of the blowing range Was well.

Since the axial fan 1″ of the second embodiment also has a basic configuration similar to that of the axial fan 1 of the first embodiment, the following description will focus on different parts and description of similar parts may be omitted.

FIG. 8 is a plan view schematically illustrating the axial fan 1″ of the second embodiment seen from the discharge port 2 side.

Note that the base part 32 and the connection part 33 are omitted in FIG. 8.

As shown in FIG. 8, the axial fan 1″ includes the discharge port side inner peripheral face 37 divided into eight substantially equal portions in the circumferential direction as inner face parts (inner face part 37 a 1 (see a range indicated by a solid line arrow), 37 b 1 (see a range indicated by a dotted line arrow), 37 a 2 (see a range indicated by a solid line arrow), 37 b 2 (see a range indicated by a dotted line arrow), 37 a 3 (see a range indicated by a solid line arrow), 37 b 3 (see a range indicated by a dotted line arrow), 37 a 4 (see a range indicated by a solid line arrow), and 37 b 4 (see a range indicated by a dotted line arrow)).

The four inner face parts 37 a 1, 37 a 2, 37 a 3 and 37 a 4 of the eight inner face parts have an inner face part angle of θ1 as in the case of the inner face part 37 a 1 of the first embodiment, and on the other hand, the remaining four inner face parts 37 b 1, 37 b 2, 37 b 3 and 37 b 4 have an inner face part angle of θ2 as in the case of the inner face part 37 b 1 of the first embodiment.

When the discharge port side inner peripheral face 37 is configured to have such inner face parts, as described in the first embodiment, the flow of a gas guided by the alternately appearing inner face parts 37 a 1, 37 a 2, 37 a 3 and 37 a 4 and discharged from the discharge port 2 spreads outward, and on the other hand, the flow of a gas guided by the alternately appearing inner face parts 37 b 1, 37 b 2, 37 b 3 and 37 b 4 and discharged from the discharge port 2 does not spread outward much.

However, what is different from the first embodiment is that since the inner face parts 37 a 1, 37 a 2, 37 a 3 and 37 a 4 are provided alternately and densely in the circumferential direction of the discharge port side inner peripheral face 37, the flow of the gas discharged from the discharge port 2 is a revolving flow and the gas guided by the inner face parts 37 a 1, 37 a 2, 37 a 3 and 37 a 4 constitutes an outwardly spread circular blowing range W.

Similarly, since the inner face parts 37 b 1, 37 b 2, 37 b 3 and 37 b 4 are provided alternately and densely in the circumferential direction of the discharge port side inner peripheral face 37, the flow of the gas discharged from the discharge port 2 is a revolving flow and the gas guided by the inner face parts 37 b 1, 37 b 2, 37 b 3 and 37 b 4 constitutes a circular blowing range W that does not spread outward much.

As a result, the blowing range W has a relatively wide circular shape and the flow of the gas is formed inside as well as outside the blowing range W, and therefore it is possible to avoid a case where a gas flow is not formed inside much with the conventional axial fan whose blowing range W is a wide circular shape, and it is possible to cool the cooling target suitably irrespective of the size of the cooling target.

For this reason, when the axial fan 1″ of the second embodiment is designed so as to have a relatively wide blowing range, if the cooling targets are small, the cooling efficiency is improved for the small cooling targets compared to the conventional axial fan which cannot efficiently cool such targets.

When the axial fan 1″ of the second embodiment is designed so as to have a small blowing range, if the cooling targets are large, the cooling efficiency is improved for the large cooling targets compared to the conventional axial fan which cannot efficiently cool such targets.

The present disclosure has been described based on the embodiments so far, but the present disclosure is not limited to the embodiments, and can be modified in various ways without departing from the spirit and scope of the present disclosure.

For example, although there are eight inner face parts in the second embodiment, in terms of inner face part angles, there are only two inner face part angles of angle θ1 and angle θ2.

However, an inner face part may be provided which has an inner face part angle θ3 different from the angle θ1 and the angle θ2 or more inner face parts may be provided.

In the second embodiment, the number of inner face parts need not be an even number such as 8, but may be an odd number.

Thus, the present disclosure is not limited to specific embodiments, and it is obvious for those skilled in the art from the description of the scope of claims that the present disclosure modified in various ways without departing from the spirit and scope of the present disclosure is also included in the technical scope of the present disclosure.

The present application discloses the below inventions.

An axial fan comprises a stator part. A rotor part includes an impeller. A casing includes a side wall part that encloses an outer periphery of the impeller. The side wall part comprises a discharge port side inner peripheral face provided within a predetermined range in a rotation axis direction of the rotor part from an end part of the discharge port side from which a gas is discharged. The discharge port side inner peripheral face comprises a plurality of inner face parts in a circumferential direction of the discharge port side inner peripheral face. When an angle of the inner face part with respect to the rotation axis of the rotor part is assumed to be an inner face part angle and the inner face part angle on an outwardly spreading side with respect to the rotation axis is assumed to be a positive angle, all of the respective inner face parts includes the inner face part angles at least on the discharge port side greater than 0°. The inner face parts adjacent to each other in a circumferential direction may include different inner face part angles on the discharge port side.

In the axial fan, the inner face part may include the discharge port side inner peripheral face divided into substantially equal portions in the circumferential direction.

In the axial fan, the number of the inner face parts may be two.

In the axial fan, the number of the inner face parts may be three or more.

In the axial fan, the number of the inner face parts may be an even number, and the inner face parts facing each other across the rotation axis may include a same inner face part angle on the discharge port side.

In the axial fan, the number of the inner face parts may be two, and one of the inner face parts may include a range in the circumferential direction less than half of a circumference of the discharge port side inner peripheral face.

In axial fan, the predetermined range in which the discharge port side inner peripheral face is provided may be a range equal to or less than ⅓ of a height of the side wall part of the rotor part in the rotation axis direction from an end part of the side wall part on the discharge port side. 

What is claimed is:
 1. An axial fan comprising: a discharge port; a rotation axis; an impeller; and a casing including a side wall part that encloses the impeller, wherein the side wall part includes a plurality of inner face parts in a circumferential direction on the discharge port side, and an inner face part angle is an angle of the inner face part with respect to the rotation axis, and the inner face part angle on an outwardly spreading side with respect to the rotation axis is a positive angle, and the inner face part angles are greater than 0°, and the two inner face parts adjacent to each other have different inner face part angles.
 2. The axial fan according to claim 1, wherein the inner face parts are arranged to be lined in a circumferential direction.
 3. The axial fan according to claim 1, wherein the number of the inner face parts is two.
 4. The axial fan according to claim 1, wherein the number of the inner face parts is three or more.
 5. The axial fan according to claim 4, wherein the number of the inner face parts is an even number, and two of the inner face parts facing in a radial direction include the same inner face part angle.
 6. The axial fan according to claim 1, wherein the casing includes an opening part as the discharge port, and the number of the inner face parts is two, and one of the inner face parts has a range less than half of an inner peripheral end part provided in the side wall part on the opening part side, with respect to an entire circumference of the inner peripheral end part in the circumferential direction.
 7. The axial fan according to claim 1, wherein a height of the inner face part is equal to or less than ⅓ of a height of the side wall part in a rotation axis direction. 